The present disclosure relates to an electric machine, such as a motor or generator, and in particular to a machine that has a segmented stator.
One common type of electric machine is a brushless direct current (DC) motor that consists of two major elements, a stator and a rotor. The stator typically includes a wire coil having a number of windings. The rotor typically includes permanent magnets. The rotor and stator are mechanically arranged such that the rotor can move freely with respect to the fixed stator. As a result, electromagnetic interaction between the stator and the rotor causes the rotor to move in response to polarity changes in the stator windings.
One common design has the rotor embedded as a shaft that turns inside a cylindrical stator. The stator is often made by laminating a number of disks formed of a ferrous material to form a “back iron.” The disks typically have formed therein tines, to provide a structure around which are wrapped copper wire strands to form the motor windings.
The rotor assembly typically includes a number of permanent magnets placed about a shaft. The magnets are held on the shaft by an outer sleeve. The rotor assembly is then rotatively supported within the cylindrical stator housing via low friction bearings.
In one particular DC brushless motor that was described in U.S. Pat. No. 6,538,356 which is herein incorporated by reference in its entirety, the windings are instead provided by a set of electrically conductive blade structures. Interconnections between the blade structures are provided in this motor by a set of disks connected to the ends of the blades. The disks are formed from an insulating substrate material having electrically conductive portions formed thereon, to provide the desired interconnections between the blades.
Another patent is U.S. Pat. No. 3,809,990 by Kuo et al. which is herein incorporated by reference in its entirety, and which discloses a motor having a stator. Kuo et al. discloses a four phase stator winding that is wound around a number of long stator poles in a stator. These long stator poles are disadvantageous. The windings must be wound around the stator poles, and this provides that the winding is located more distant from the rotor. This excessive distance thereby reduces the amount of electromagnetic flux and electromagnetic interaction between the winding and the rotor.